Conventionally, there have been problems such as hair showing a hard and unfavorable texture when treated with oxidation hair dye and hair bleach due to damage to the hair from those agents. Conventionally, this problem has been addressed with the application of conditioners or treatment agents such as pretreatment and/or post-treatment agents. In order to solve the above problem, for example, a hair-dying agent has been proposed which is characterized by the fact that it is a two-part hair-dying agent comprising a first agent which contains an oxidation dye intermediate and a second agent which contains an oxidizing agent, and that one or both of either the first or second agents contains egg yolk oil (laid-open patent H11-349455). Also, a hair color treatment agent has been proposed which is characterized by the fact that it is a treatment agent for hair coloring comprising a pretreatment agent and a post-treatment agent employed before and after a hair color treatment, that the pretreatment agent contains keratin hydrolysate and/or a derivative thereof, and the post-treatment agent contains at least one selected from the group made up of ceramide, a ceramide derivative, a phospholipid and a derivative of a phospholipid (laid-open patent 2002-322035). Additionally, the same document describes that the said hair color treatment further contains at least one selected from the group made up of plant-derived protein hydrolysate, a derivative of plant-derived protein hydrolysate, protein hydrolysate derived from egg whites and a derivative of protein hydrolysate derived from egg whites. However, issues arose for the above treatment agents wherein the agents were unable to sufficiently solve the problem and were sticky, and were unable to obtain a good hair texture.    Patented reference 1: Laid-Open Patent H11-349455    Patented reference 2: Laid-Open Patent 2002-322035